Why tall women and short men are becoming a thing of the past

Tomorrow’s woman is short and has a small head. Her narrow mouth sits beneath prominent cheekbones. 

She is a winner in the fertility stakes, entering menopause at a later age than her gran. 

Tomorrow’s man, meanwhile, is taller and less inclined to become a heavy smoker than today’s model.

This is the direction in which we are rapidly evolving, according to studies of newly emerging genetic mutations.

Some of these include oddities, such as people having an extra artery in their forearms and unusually bony feet.

But just 12 years ago, one of the world’s leading experts in genes and evolution — Steve Jones, an emeritus professor of human genetics at University College London (UCL) — declared that humanity had hit the evolutionary buffers.

He argued that the principle that only the fittest survived and we were continually evolving was outdated, thanks to modern healthcare and abundant food.

What’s more, Professor Jones said, far fewer children are being born from aged patriarchal sperm that harbours potential genetic mutations. This, he argued, is because it is no longer socially acceptable for much older men to have lots of children with multiple young wives.

Yet anatomists at Flinders University in Australia now take a very different view.

Their research suggests we are experiencing a rapid burst of change called a micro-evolution, where modern life exerts pressures that influence our genes to mutate.

One of the most obvious is how increasing numbers of people are born without the capacity to grow wisdom teeth, says Dr Teghan Lucas, who led the research, published in the Journal of Anatomy last month.

Our caveman ancestors needed them to replace other teeth worn down by tearing raw, chewy food. 

But as humans learnt to cook, they needed to chew less. So around 2.4 million years ago their jaws shrank, making space for the modern human brain to expand.

According to Dr Lucas, our jaws are still changing, perhaps due to the amount of processed food in modern diets, which requires even less chewing.

‘As our faces are getting a lot shorter, there is not as much room for teeth because of smaller jaws,’ she wrote.

While our faces are becoming shorter-jawed and slimmer-mouthed (leaving cheekbones more prominent), our bodies are changing, too, says Dr Lucas. Her colleagues have discovered a ‘significant increase’ in the number of people born with an extra artery in their arms.

The median artery forms in the womb as the main vessel that supplies blood to the forearm and hand. But it usually disappears during gestation, being replaced by the radial and ulnar arteries in the lower arm.

The prevalence of the median artery into adulthood was around 10 per cent in people born in the mid-1880s, compared with 30 per cent in people born in the late 20th century.

‘It is a significant increase in a fairly short period of time,’ Dr Lucas wrote. ‘If this trend continues, a majority of people will have a median artery of the forearm by 2100.’

Retaining this artery increases our overall blood supply. It may also be a handy spare part, to be used as a replacement artery for other parts of the body, during surgery for example.

But this hardly sounds like a strong evolutionary advantage. Nor does an increase of people born with extra bones in their feet, as also reported in the Journal of Anatomy.

Dr Lucas suggests that such changes are occurring because advances in medicine, from IVF treatment to antibiotics, mean we no longer eject pointless mutations from the gene pool.

She cites the example of people who are infertile, saying: ‘Natural selection would dictate that they do not have the opportunity to pass on their genes, however due to modern medicine they can now reproduce.’

Our fertility genes may themselves be adapting to meet the challenges of modern lifestyles.

In April, a study in the journal BMC Women’s Health concluded that women may soon stay fertile significantly longer, in response to pressures that push them to have babies later in life.

Dr Rama Shankar Singh, a professor of biology at McMaster University in Canada, says his study of more than 700 middle-aged women from six ethnic groups suggests there are no concrete biological mechanisms that force human menopause to occur at a particular time in a woman’s life. Instead, modern social forces, such as delayed marriage and reproduction, may well push menopause back to occur much later in life.

‘Menopause is a changing, evolving trait that is still very dynamic,’ says Professor Singh.

Mark Thomas, a professor of evolutionary genetics at University College London, says such changes are typical of how humankind is evolving, particularly in the sphere of fertility.

He adds that evidence from the UK Biobank data on more than half a million people and their DNA shows that in the past generation alone, genes that prompt a shorter height in women are becoming more dominant. Men, meanwhile, are getting taller. But why this might be so is not clear.

Even our diet can affect our genes. Scientists from Cornell University, New York, have discovered how families who practise vegetarianism for generations evolve a mutation of a digestive gene called FADS2.

This enables them to efficiently process omega-3 and omega-6 fatty acids from non-meat sources into essential brain nutrients, they reported in the journal Molecular Biology and Evolution in 2016.

However, while some health-boosting habits are encouraging specific genes to proliferate, other genetic types are being erased because of their link to unhealthy lifestyles.

In particular, a mutated gene called CHRNA3 is not being passed down as often, say scientists at Columbia University in New York City.

In men the gene is associated with being attracted to nicotine, becoming a heavy smoker and an increased susceptibility to lung cancer.

Molly Przeworski, a professor of evolutionary biology at Columbia, says that the gene mutation is dwindling noticeably. 

‘It may be that men who don’t carry it can survive to have more children, or that men without the gene live longer and can help with their grandchildren, improving their families’ chances of survival.’

It seems human evolution is composing its own tobacco warning: stub out the unhealthy habit, or Mother Nature will weed you out.

Under the microscope

Michelin star chef and Masterchef judge, Marcus Wareing, 50, takes our health quiz.

Can you run up the stairs?

Yes. My fitness routine involves weights, running and cardiovascular workouts three or four times a week. I have a gym at home so have worked out there through lockdown. I also cycle on Wimbledon Common, near where we live.

Get your five a day?

No. I try to eat a balanced diet but don’t eat much fruit and veg.

Ever dieted?

No, but I watch what I eat. I’m cautious about not eating too late. If I’m putting on a few pounds, I’ll cut out sugar or meals and can lose the weight within a week (I weigh around 11 st 4 lb and am 5 ft 10 in tall).

How has the pandemic affected you?

It’s been the toughest time I’ve ever had. During the last lockdown I found it very difficult and scary not being in the kitchen and not having a business. I drank far too much. My wife Jane and I followed the rules strictly — staying inside with our children Jake, 19, Archie, 15, and Jessie, 13.

Any vices?

Wine and tidiness — I don’t understand how kids can leave their shoes at the door when the cupboard to put them in is right there.

Any family ailments?

My mum, who’s 79, has dementia, but no illnesses have run through my family. My dad, who is 80, is a rock.

Worst illness/injury?

I broke a bone at the bottom of my spine when skiing in 2012. It took weeks to heal and I was on opioids for the pain. But I didn’t realise you’re supposed to wean yourself off them. When I stopped taking them after a week, I had this weird taste in my mouth, dark thinking and couldn’t sleep. I then had to go back on them in order to come off them slowly. It took me three weeks to recover from that.

Pop any pills?

Fish oil, B vitamins and vitamin D daily. I’ve also taken a statin for two years.

Ever have plastic surgery?

God no! I love looking old.

Cope well with pain?

I hit it head on. But you need to rest while your body is fighting something.

Tried alternative remedies?

Acupuncture for muscle pain after I came off a motorbike around five years ago. I remember the therapist putting needles into my back and I asked why was he flicking them. He wasn’t; the muscle was vibrating. I haven’t had problems there since.

Ever been depressed?

I’ve been down for the past few months of Covid-19. I don’t have depression, though.

Hangover cure?

A pot of coffee.

Like to live for ever?

No. We have a start and a finish. I want to live for as long as I can but not for ever. Maybe to 100.

MasterChef: The Professionals starts tonight at 9pm on BBC1.